1. Field of the Invention
The invention relates to a manufacturing method and a processing system, and more particularly, relates to a method of manufacturing semiconductor and an exposure system.
2. Description of Related Art
With increasing IC integration level, dimensions of patterns are also gradually reduced day by day, thus, how to align multiple layers in a device has become one of important factors in manufacturing semiconductor. In other words, each layer must be accurately aligned to the others, so that circuits formed therein may match layout patterns and operate normally. Alignment is a critical step in a lithography process because a wafer needs to be aligned with patterns produced in previous steps in addition to be aligned in position and levelness on an exposure machine. Particularly, an accuracy in the alignment may influence critical dimension, property, and performance of the IC, as well as a production yield of the wafer. Accordingly, it is required to effectively monitor alignment behaviors between layers in a semiconductor device.
Generally, a method of monitoring the alignment behaviors is mainly done by setting control values of different items to the exposure machine, such that when an actual value measured after exposing the wafer deviates from the control value of one item set to the exposure machine, the exposure machine may send a warning and reject the wafer. In this case, the wafer to which the warning is targeted may require further detection or reworks. However, if a range for setting the control values is improper or requires frequent adjustments, which will cause false warnings and unnecessary reworks to seriously influence productivity and waste resources on production line. Therefore, how to effectively monitor the alignment behaviors between layers while reducing a frequency of the false warning is an important issue to be discussed in the field.